From eb2d4cb5414361d9148bf43388012dcbdce80abe Mon Sep 17 00:00:00 2001 From: Zalathar Date: Sun, 26 Nov 2023 22:20:16 +1100 Subject: [PATCH] coverage: Skip spans that can't be un-expanded back to the function body When we extract coverage spans from MIR, we try to "un-expand" them back to spans that are inside the function's body span. In cases where that doesn't succeed, the current code just swaps in the entire body span instead. But that tends to result in coverage spans that are completely unrelated to the control flow of the affected code, so it's better to just discard those spans. --- .../src/coverage/spans/from_mir.rs | 12 +++++++----- tests/coverage/async.cov-map | 12 ++++++------ tests/coverage/async2.cov-map | 12 ++++++------ tests/coverage/inline.cov-map | 4 ++-- tests/coverage/inline.coverage | 2 +- tests/coverage/unreachable.cov-map | 12 ++++++------ tests/coverage/unreachable.coverage | 4 ++-- 7 files changed, 30 insertions(+), 28 deletions(-) diff --git a/compiler/rustc_mir_transform/src/coverage/spans/from_mir.rs b/compiler/rustc_mir_transform/src/coverage/spans/from_mir.rs index 6189e5379ea..e1531f2c239 100644 --- a/compiler/rustc_mir_transform/src/coverage/spans/from_mir.rs +++ b/compiler/rustc_mir_transform/src/coverage/spans/from_mir.rs @@ -63,14 +63,14 @@ fn bcb_to_initial_coverage_spans<'a, 'tcx>( let statement_spans = data.statements.iter().filter_map(move |statement| { let expn_span = filtered_statement_span(statement)?; - let span = function_source_span(expn_span, body_span); + let span = unexpand_into_body_span(expn_span, body_span)?; Some(CoverageSpan::new(span, expn_span, bcb, is_closure(statement))) }); let terminator_span = Some(data.terminator()).into_iter().filter_map(move |terminator| { let expn_span = filtered_terminator_span(terminator)?; - let span = function_source_span(expn_span, body_span); + let span = unexpand_into_body_span(expn_span, body_span)?; Some(CoverageSpan::new(span, expn_span, bcb, false)) }); @@ -180,14 +180,16 @@ fn filtered_terminator_span(terminator: &Terminator<'_>) -> Option { /// Returns an extrapolated span (pre-expansion[^1]) corresponding to a range /// within the function's body source. This span is guaranteed to be contained /// within, or equal to, the `body_span`. If the extrapolated span is not -/// contained within the `body_span`, the `body_span` is returned. +/// contained within the `body_span`, `None` is returned. /// /// [^1]Expansions result from Rust syntax including macros, syntactic sugar, /// etc.). #[inline] -fn function_source_span(span: Span, body_span: Span) -> Span { +fn unexpand_into_body_span(span: Span, body_span: Span) -> Option { use rustc_span::source_map::original_sp; + // FIXME(#118525): Consider switching from `original_sp` to `Span::find_ancestor_inside`, + // which is similar but gives slightly different results in some edge cases. let original_span = original_sp(span, body_span).with_ctxt(body_span.ctxt()); - if body_span.contains(original_span) { original_span } else { body_span } + body_span.contains(original_span).then_some(original_span) } diff --git a/tests/coverage/async.cov-map b/tests/coverage/async.cov-map index 857e0a536a7..e4354a1af87 100644 --- a/tests/coverage/async.cov-map +++ b/tests/coverage/async.cov-map @@ -74,28 +74,28 @@ Number of file 0 mappings: 6 = ((c0 + c1) - c1) Function name: async::executor::block_on::VTABLE::{closure#0} -Raw bytes (9): 0x[01, 01, 00, 01, 01, 72, 11, 00, 33] +Raw bytes (9): 0x[01, 01, 00, 01, 01, 72, 11, 00, 31] Number of files: 1 - file 0 => global file 1 Number of expressions: 0 Number of file 0 mappings: 1 -- Code(Counter(0)) at (prev + 114, 17) to (start + 0, 51) +- Code(Counter(0)) at (prev + 114, 17) to (start + 0, 49) Function name: async::executor::block_on::VTABLE::{closure#1} -Raw bytes (9): 0x[01, 01, 00, 01, 01, 73, 11, 00, 33] +Raw bytes (9): 0x[01, 01, 00, 01, 01, 73, 11, 00, 31] Number of files: 1 - file 0 => global file 1 Number of expressions: 0 Number of file 0 mappings: 1 -- Code(Counter(0)) at (prev + 115, 17) to (start + 0, 51) +- Code(Counter(0)) at (prev + 115, 17) to (start + 0, 49) Function name: async::executor::block_on::VTABLE::{closure#2} -Raw bytes (9): 0x[01, 01, 00, 01, 01, 74, 11, 00, 33] +Raw bytes (9): 0x[01, 01, 00, 01, 01, 74, 11, 00, 31] Number of files: 1 - file 0 => global file 1 Number of expressions: 0 Number of file 0 mappings: 1 -- Code(Counter(0)) at (prev + 116, 17) to (start + 0, 51) +- Code(Counter(0)) at (prev + 116, 17) to (start + 0, 49) Function name: async::executor::block_on::VTABLE::{closure#3} Raw bytes (9): 0x[01, 01, 00, 01, 01, 75, 11, 00, 13] diff --git a/tests/coverage/async2.cov-map b/tests/coverage/async2.cov-map index cc7aed9aee3..23f26ee4e5f 100644 --- a/tests/coverage/async2.cov-map +++ b/tests/coverage/async2.cov-map @@ -78,28 +78,28 @@ Number of file 0 mappings: 6 = ((c0 + c1) - c1) Function name: async2::executor::block_on::VTABLE::{closure#0} -Raw bytes (9): 0x[01, 01, 00, 01, 01, 2b, 11, 00, 33] +Raw bytes (9): 0x[01, 01, 00, 01, 01, 2b, 11, 00, 31] Number of files: 1 - file 0 => global file 1 Number of expressions: 0 Number of file 0 mappings: 1 -- Code(Counter(0)) at (prev + 43, 17) to (start + 0, 51) +- Code(Counter(0)) at (prev + 43, 17) to (start + 0, 49) Function name: async2::executor::block_on::VTABLE::{closure#1} -Raw bytes (9): 0x[01, 01, 00, 01, 01, 2c, 11, 00, 33] +Raw bytes (9): 0x[01, 01, 00, 01, 01, 2c, 11, 00, 31] Number of files: 1 - file 0 => global file 1 Number of expressions: 0 Number of file 0 mappings: 1 -- Code(Counter(0)) at (prev + 44, 17) to (start + 0, 51) +- Code(Counter(0)) at (prev + 44, 17) to (start + 0, 49) Function name: async2::executor::block_on::VTABLE::{closure#2} -Raw bytes (9): 0x[01, 01, 00, 01, 01, 2d, 11, 00, 33] +Raw bytes (9): 0x[01, 01, 00, 01, 01, 2d, 11, 00, 31] Number of files: 1 - file 0 => global file 1 Number of expressions: 0 Number of file 0 mappings: 1 -- Code(Counter(0)) at (prev + 45, 17) to (start + 0, 51) +- Code(Counter(0)) at (prev + 45, 17) to (start + 0, 49) Function name: async2::executor::block_on::VTABLE::{closure#3} Raw bytes (9): 0x[01, 01, 00, 01, 01, 2e, 11, 00, 13] diff --git a/tests/coverage/inline.cov-map b/tests/coverage/inline.cov-map index 72b10fd0cc2..001c333ae6d 100644 --- a/tests/coverage/inline.cov-map +++ b/tests/coverage/inline.cov-map @@ -15,12 +15,12 @@ Number of file 0 mappings: 5 = ((c0 + c1) - c1) Function name: inline::error -Raw bytes (9): 0x[01, 01, 00, 01, 01, 31, 01, 02, 02] +Raw bytes (9): 0x[01, 01, 00, 01, 01, 31, 01, 01, 14] Number of files: 1 - file 0 => global file 1 Number of expressions: 0 Number of file 0 mappings: 1 -- Code(Counter(0)) at (prev + 49, 1) to (start + 2, 2) +- Code(Counter(0)) at (prev + 49, 1) to (start + 1, 20) Function name: inline::length:: Raw bytes (9): 0x[01, 01, 00, 01, 01, 1e, 01, 02, 02] diff --git a/tests/coverage/inline.coverage b/tests/coverage/inline.coverage index 6efd9a0830b..68a2e408306 100644 --- a/tests/coverage/inline.coverage +++ b/tests/coverage/inline.coverage @@ -50,5 +50,5 @@ LL| |#[inline(always)] LL| 0|fn error() { LL| 0| panic!("error"); - LL| 0|} + LL| |} diff --git a/tests/coverage/unreachable.cov-map b/tests/coverage/unreachable.cov-map index 495419820c1..55d124a16f5 100644 --- a/tests/coverage/unreachable.cov-map +++ b/tests/coverage/unreachable.cov-map @@ -1,24 +1,24 @@ Function name: unreachable::UNREACHABLE_CLOSURE::{closure#0} -Raw bytes (9): 0x[01, 01, 00, 01, 01, 0f, 27, 00, 49] +Raw bytes (9): 0x[01, 01, 00, 01, 01, 0f, 27, 00, 47] Number of files: 1 - file 0 => global file 1 Number of expressions: 0 Number of file 0 mappings: 1 -- Code(Counter(0)) at (prev + 15, 39) to (start + 0, 73) +- Code(Counter(0)) at (prev + 15, 39) to (start + 0, 71) Function name: unreachable::unreachable_function -Raw bytes (9): 0x[01, 01, 00, 01, 01, 11, 01, 02, 02] +Raw bytes (9): 0x[01, 01, 00, 01, 01, 11, 01, 01, 25] Number of files: 1 - file 0 => global file 1 Number of expressions: 0 Number of file 0 mappings: 1 -- Code(Counter(0)) at (prev + 17, 1) to (start + 2, 2) +- Code(Counter(0)) at (prev + 17, 1) to (start + 1, 37) Function name: unreachable::unreachable_intrinsic -Raw bytes (9): 0x[01, 01, 00, 01, 01, 16, 01, 02, 02] +Raw bytes (9): 0x[01, 01, 00, 01, 01, 16, 01, 01, 2c] Number of files: 1 - file 0 => global file 1 Number of expressions: 0 Number of file 0 mappings: 1 -- Code(Counter(0)) at (prev + 22, 1) to (start + 2, 2) +- Code(Counter(0)) at (prev + 22, 1) to (start + 1, 44) diff --git a/tests/coverage/unreachable.coverage b/tests/coverage/unreachable.coverage index fa0ac9ccfa1..7015bb90aa3 100644 --- a/tests/coverage/unreachable.coverage +++ b/tests/coverage/unreachable.coverage @@ -16,12 +16,12 @@ LL| | LL| 0|fn unreachable_function() { LL| 0| unsafe { unreachable_unchecked() } - LL| 0|} + LL| |} LL| | LL| |// Use an intrinsic to more reliably trigger unreachable-propagation. LL| 0|fn unreachable_intrinsic() { LL| 0| unsafe { std::intrinsics::unreachable() } - LL| 0|} + LL| |} LL| | LL| |#[coverage(off)] LL| |fn main() {